use SPDX license name

package.json

@@ -2,7 +2,7 @@
   "name": "lesspass-cozy",
   "version": "1.1.0",
   "description": "LessPass cozy app",
-  "license": "GPLv3",
+  "license": "GPL-3.0",
   "author": "Guillaume Vincent <guillaume@oslab.fr>",
   "main": "src/app.js",
   "repository": "lesspass/cozy",